1. Field of the Invention
The present invention relates to a battery gauging device, and in particular, to a battery gauging device, which can exactly display on a terminal the charged capacity of a chargable battery in the course of charging.
2. Description of the Prior Art
FIG. 1 is a block diagram illustrating the conventional battery gauging device in a mobile telecommunication terminal during a battery charging.
Referring to FIG. 1, the conventional battery gauging device in a mobile telecommunication terminal during a battery charging comprises: a charger 101 for converting a received alternate current (AC) to a direct current (DC), and controlling the charging and discharging of a battery 102a; a battery pack 102 for receiving the DC, and charging an electric charge into the battery 102a; and a mobile telecommunication terminal 103 for receiving an output voltage BAT+ of the battery pack 102, and displaying the charged capacity of the battery 102a by measuring the voltage BAT+ of the battery 102a. 
Here, the battery pack 102 comprises: the battery 102a for charging the electric charge; a charging/discharging controller 102b for controlling charging and discharging of the battery 102a, and protecting a circuit; and a switch 102c for switching on or off the DC inputted to the battery 102a under a control by the charging/discharging controller 102b. 
The mobile telecommunication terminal 103 comprises: a system electric power section 103a for receiving the DC voltage BAT+ outputted from the battery pack 102, and supplying the power of the system; a battery gauging section 103b for converting a level of the DC voltage BAT+ to a digital signal; and a mobile station modem 103c as a microprocessor for receiving the digital signal from the battery gauging section 103b, and displaying the capacity of the battery 102a on the display section 103c. 
A thermistor 102d is connected to a ground terminal of the battery 102a, which converts the temperature of the battery 102a to an electric signal, to control charging and discharging of the battery 102a in accordance with the temperature. The charger 101 detects a voltage TH of the thermistor 102d, and checks the temperature of the battery 102a to control the charging and discharging of the battery 102 in accordance with the temperature.
The following is a brief explanation of an operation of the battery gauging device during a battery charging of a mobile telecommunication terminal having the above construction.
Once inputted to the charger 101, the AC is converted to the DC of a proper level required to charge the battery pack 102, and outputted. The DC is applied to the battery 102 through the switch 102c so as to charge the battery 102a. 
The charging/discharging controller 102b is connected to the positive terminal + and a negative terminal to detect the voltage of the battery 102a, and interrupts charging by switching off the switch 102c when the voltage of the battery 102a reaches a predetermined value.
The charging/discharging controller 102b plays a role of preventing an excessive charge of the battery 102a above a predetermined voltage as well as of preventing an excessive discharge below a predetermined voltage. The charging/discharging controller 102 also plays a role of preventing an excessive current due to a short as well as protecting a circuit by preventing charging under the temperature higher than a predetermined one.
The DC inputted from the charger 101 to the battery pack 102 charges the battery 102a, and supplies an electric power to the terminal 103 while the charged voltage becomes an output voltage BAT+ of the battery pack 102 and is inputted to the terminal 103 for charging.
To be specific, the voltage of the battery 102a is not inputted to the terminal 103 during the charging. Instead, the DC voltage inputted from the charger 101 to the battery pack 102 is inputted to the terminal 103.
If the output voltage BAT+ of the battery pack 102 is inputted to the terminal 103, it is detected by the MSM 103c, which subsequently transmits a xe2x80x9cswitch-onxe2x80x9d signal to the electric power section 103a of the system so as to receive the output voltage BAT+ of the battery pack 102 and supply a power to the terminal 103.
At this stage, the battery gauging section 103b receives the voltage BAT+ inputted from the terminal 103 from the system electric power section 103a, and converts the voltage level to a digital signal for transmission to the MSM 103c. Then, the MSM 103c displays a capacity of the battery 102a through the display section 103d in accordance with the transmitted digital signal.
As described above, however, the DC inputted to the battery pack 102 from the charger 101 charges the battery 102a, and at the same time, the output voltage BAT+ is inputted to the terminal 103 so that the voltage of the battery 102a may not be inputted to the terminal 103 during the charging but that the DC voltage inputted from the charger 101 to the battery pack 102 can be inputted to the terminal.
Thus, the output voltage BAT+ of the battery pack 102, which has been received from the system electric power section 103a by the battery gauging section 103b of the terminal 103 is not a voltage from the battery 102a but the voltage from the charger 101. Therefore, the charged capacity of the battery 102 displayed on the display section 103d is always indicated to be full.
As described above, the conventional battery gauging device during a battery charging has a drawback of failing to display a capacity of the battery because of inability to measure voltage of the battery 102a since the DC voltage inputted from the charger 101 is inputted directly to the power supply of the terminal 103 during the battery charging.
It is, therefore, an object of the present invention to provide a battery gauging device during a battery charging, which can exactly display the charged capacity of a battery even in the course of a battery charging by regularly interrupting the voltage inputted to the battery and measuring the voltage of the battery at that time during the charging.
To achieve the above object, there is provided a battery gauging device during a battery charging according to the present invention, comprising: a charger for converting an AC voltage to a DC voltage, and outputting the converted voltage; a battery pack including a battery for charging an electric charge, first switching means for switching on/off the DC voltage, and second switching means being switched on/off by a battery charge enable (BCE) signal so as to temporarily discharging the charged capacity during the battery charging; and a terminal including a battery gauging section for gauging charged capacity inputted from the battery pack, and a microprocessor for outputting the BCE signal to the switching means, and displaying the gauged value to the display section.
Preferably, the battery pack includes a charging/discharging controller for controlling charging and discharging of the battery and protecting an internal circuit by controlling switch on/off of the first switching means so as to control supply of the DC voltage inputted from the charger to the battery; and temperature detection means connected to a ground terminal of the battery for detecting temperature of the battery, and converting the temperature value to an electric signal for output of the same.
Preferably, the terminal includes a system electric power section for receiving an output voltage of the battery pack from the terminal, and supplying a power to constitutional elements inside thereof, and outputting a voltage for battery gauging to the battery gauging section.
Preferably, the first and the second switching means are field effect transistors (FET).
More preferably, the second switching means is positioned between the first switching means and positive terminal of the battery.
According to the present invention constructed above, the charged capacity of a battery can be exactly read and displayed on the terminal even during the battery charging.